Nickel catalysts acylation

Treatment of A and B with hydrogen over a nickel catalyst results in quantitative conversion of each compound to ferf-butyl alcohol. A reacts with acyl halides and anhydrides, whereas B is unaffected by these reagents. Treatment of 1 mole of A with excess methylmagnesium iodide in diethyl ether solution produces 1 mole of methane and 1 moie each of ferf-butyl alcohol and methanol. One mole of B with excess methylmagnesium iodide produces 1 mole of 2-methoxy-2-methylpropene and 1 mole of ferf-butyl alcohol. 

Finally, the hydrazides 3 5 are easily transformed to the corresponding enantiomerically pure a-hydrazino and a-amino acid derivatives16. In a representative example hydrazido acid 3 (R = C6H5) is esterified (CH2N2) and deprotected to 6 with trifluoroacetic acid. The resulting solution is directly hydrogenated over a Raney nickel catalyst. The unpurified amino acid is acylated with ( + )-(5 )-methoxy(trifluoromethyl)phenylacetyl chloride [( + )-MTPA-Cl], to afford the amide 7 in 99% overall yield for the three steps. 

Acylhydrazones, particularly those embodying an electron-deficient acyl group (e.g., 4-trifluoromethylbenzoyl ), condense with silyl ketene acetals in the presence of Sc(OTf)j. The efficiency can be judged by a quantitative reaction utilizing 5 mol% of ScjOTf), versus the second best reaction (42%) which requires 100 mol% of the Lewis acid BFj OEtj. Since the N-N bond of the products is easily cleaved by hydrogenation (Raney nickel catalyst), a convenient route to 3-amino esters is developed. 

In the presence of a nickel catalyst, alkynes can be inserted into bonds between tin and an alkynyl, allyl, or acyl group, to give new vinylstannanes.54-60 Examples from this rapidly developing field are shown in equations 8-23 to 8-25 57... 

The ethylene oligomerization catalyst cycle in the presence of nickel catalyst, HNiYL (where, Y = acyl, carboxyl, halogen L = phosphine), is shown in the following reaction series [71] ... 

Analogous decarbonylation reactions were observed with acyl halides [18], esters [19], acyl cyanides [20], thioesters [21], selenoesters [21b], acylphospho-nates [22], and even ketones (preceding chapters). Acid anhydrides underwent a fragmentation reaction upon treatment with a nickel catalyst to afford alkenes,... 

Azanickelacycle formation with partial replacement of the heterocyclic moiety substance by the nickel catalyst was also employed for the synthesis of indoles, an important class of heterocycles found in natural products and pharmaceuticals. Maizum et al. demonstrated a nickel-catalyzed decarbonylative cycloaddition by which anthranilic acid derivatives 39, which are readily available, react with alkynes to afford substituted indoles 41 (Scheme 12.17) [20]. The reaction is supposed to proceed via oxidative addition and decarbonylation to afford azanickelacycle 40, followed by alkyne insertion, 1,3-acyl migration, and reductive elimination, to afford A-pivaloyl-protected indole 41. Deprotected indole 42 was obtained as the final product upon workup, that is, treatment of the reaction crude reaction mixture with NaSMe in MeOH. 

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